Event Notification Report for March 14, 2002
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
03/13/2002 - 03/14/2002
EVENT NUMBERS
38771
Fuel Cycle Facility
Event Number: 38771
Facility: PORTSMOUTH GASEOUS DIFFUSION PLANT
Region: 3 State: OH
Unit: [] [] []
RX Type: URANIUM ENRICHMENT FACILITY
Comments: 2 DEMOCRACY CENTER
6903 ROCKLEDGE DRIVE
BETHESDA, MD 20817 (301)564-3200
NRC Notified By: ERIC SPAETH
HQ OPS Officer: BOB STRANSKY
Region: 3 State: OH
Unit: [] [] []
RX Type: URANIUM ENRICHMENT FACILITY
Comments: 2 DEMOCRACY CENTER
6903 ROCKLEDGE DRIVE
BETHESDA, MD 20817 (301)564-3200
NRC Notified By: ERIC SPAETH
HQ OPS Officer: BOB STRANSKY
Notification Date: 03/15/2002
Notification Time: 12:55 [ET]
Event Date: 03/14/2002
Event Time: 15:00 [EST]
Last Update Date: 03/15/2002
Notification Time: 12:55 [ET]
Event Date: 03/14/2002
Event Time: 15:00 [EST]
Last Update Date: 03/15/2002
Emergency Class: NON EMERGENCY
10 CFR Section:
10 CFR Section:
Person (Organization):
MONTE PHILLIPS (R3)
FRED BROWN (NMSS)
MONTE PHILLIPS (R3)
FRED BROWN (NMSS)
24-HOUR NRC BULLETIN 91-01 REPORT
"During Field-testing of the west annex floor, the floor failed to maintain the solution in a safe slab by allowing water to seep in cracks along the wall. This is a violation of NCSA- 0705_076 (inadvertent containers) administrative controls on potential inadvertent containers. While an unsafe amount of solution was NOT lost in this event, the cracks represent a loss of one leg of double contingency control as defined in NCSE- 0705_076.
"Background information: On March 6, a low level probe for the storage columns in the West Annex developed a leak and allowed uranium-bearing solution to accumulate on the floor. The amount of spilled solution on the floor was estimated at that time to be no more than 18.4 liters. The spill amount did not meet the definition of an unsafe amount of uranium bearing material, the process conditions credited for meeting double contingency in the NCSE's were maintained.
"On March 14, after completing repairs to the low level probe, the solution level in the West Annex storage columns was remeasured. The solution volume lost, calculated from the system sight glasses was calculated to be approximately 97.5 liters. Given the known assay and concentration of uranium, the spilled solution still did not represent an unsafe amount of uranium bearing material even when the volume was increased from 18.4 liters to 97.5 liters.
"On March 14, an NCS engineer and Operations personnel investigated the difference between the amount of solution observed on the floor and the amount estimated by the level of the sight glass. A field test was conducted where as water was observed to seep into cracks between the floor and the wall.
"SAFETY SIGNIFICANCE OF EVENTS: Low. The solution in question could not support a criticality in any geometry. Less than a safe mass amount of solution was involved.
"POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO[S] OF HOW CRITICALITY COULD OCCUR):
For a criticality to occur, the following events are required. The West Annex blending system would have to be operating and processing solution with a high concentration of uranium and assay. Then a leak would have to occur such that an unsafe amount of solution would collect on the floor. The solution would then flow into the cracks on the floor into an unsafe geometry. Depending on the amount of solution collected some reflection would be required to maintain a critical chain reaction.
"CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC.): N/A. Volume or Geometry
"ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE OF CRITICAL MASS): Based upon the amount of solution that leaked on the floor, 51 grams U235. This represents 3% of the required amount of solution
"NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES: Cracks between the floor and the wall could allow solution to enter an unknown unfavorable geometry in the event of a spill.
"CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEM AND WHEN EACH WAS IMPLEMENTED: The PSS directed remaining in an anomalous condition until the repairs to the cracks can be made."
"During Field-testing of the west annex floor, the floor failed to maintain the solution in a safe slab by allowing water to seep in cracks along the wall. This is a violation of NCSA- 0705_076 (inadvertent containers) administrative controls on potential inadvertent containers. While an unsafe amount of solution was NOT lost in this event, the cracks represent a loss of one leg of double contingency control as defined in NCSE- 0705_076.
"Background information: On March 6, a low level probe for the storage columns in the West Annex developed a leak and allowed uranium-bearing solution to accumulate on the floor. The amount of spilled solution on the floor was estimated at that time to be no more than 18.4 liters. The spill amount did not meet the definition of an unsafe amount of uranium bearing material, the process conditions credited for meeting double contingency in the NCSE's were maintained.
"On March 14, after completing repairs to the low level probe, the solution level in the West Annex storage columns was remeasured. The solution volume lost, calculated from the system sight glasses was calculated to be approximately 97.5 liters. Given the known assay and concentration of uranium, the spilled solution still did not represent an unsafe amount of uranium bearing material even when the volume was increased from 18.4 liters to 97.5 liters.
"On March 14, an NCS engineer and Operations personnel investigated the difference between the amount of solution observed on the floor and the amount estimated by the level of the sight glass. A field test was conducted where as water was observed to seep into cracks between the floor and the wall.
"SAFETY SIGNIFICANCE OF EVENTS: Low. The solution in question could not support a criticality in any geometry. Less than a safe mass amount of solution was involved.
"POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO[S] OF HOW CRITICALITY COULD OCCUR):
For a criticality to occur, the following events are required. The West Annex blending system would have to be operating and processing solution with a high concentration of uranium and assay. Then a leak would have to occur such that an unsafe amount of solution would collect on the floor. The solution would then flow into the cracks on the floor into an unsafe geometry. Depending on the amount of solution collected some reflection would be required to maintain a critical chain reaction.
"CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC.): N/A. Volume or Geometry
"ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE OF CRITICAL MASS): Based upon the amount of solution that leaked on the floor, 51 grams U235. This represents 3% of the required amount of solution
"NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES: Cracks between the floor and the wall could allow solution to enter an unknown unfavorable geometry in the event of a spill.
"CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEM AND WHEN EACH WAS IMPLEMENTED: The PSS directed remaining in an anomalous condition until the repairs to the cracks can be made."